Digital video capabilities can be incorporated into a wide range of devices, including digital televisions, digital direct broadcast systems, wireless communication devices, personal digital assistants (PDAs), laptop computers, desktop computers, video game consoles, digital cameras, digital recording devices, cellular or satellite radio telephones, and the like. Digital video devices can provide significant improvements over conventional analog video systems in processing and transmitting video sequences.
Different video encoding standards have been established for encoding digital video sequences. The Moving Picture Experts Group (MPEG), for example, has developed a number of standards including MPEG-1, MPEG-2 and MPEG-4. Other examples include the International Telecommunication Union (ITU)-T H.263 standard, and the emerging ITU-T H.264 standard and its counterpart, ISO/IEC MPEG-4, Part 10, i.e., Advanced Video Coding (AVC). These video encoding standards support improved transmission efficiency of video sequences by encoding data in a compressed manner.
Dynamic rate adaptation techniques are used to adjust the number of coding bits, i.e., the coding rate, allocated to a video stream. Coding rates may be adjusted to ensure that the encoded video sequence conforms to quality requirements and/or changes to the available bandwidth caused by varying network conditions. Some rate control techniques are designed to produce a constant coding rate, while other rate control techniques are designed to produce constant quality. Dynamic rate adaptation techniques may balance coding rate and quality level, and be responsive to network congestion conditions and video frame content.